I have no idea what the module does in technical terms, as I don't speak that language, but I will give you my overall impressions or to say it better, my feeling after playing the modded Etherwave for almost 2 weeks.

What I love about the theremin as an instrument is that it is new, somehow yet unexplored and full of potential no matter what kind of music you play.

The truth is however, that after a certain time of messing with the Etherwave you feel like a chained dog who is waiting for his master outside of a supermarket. You feel like "Hey it's something there, let me get it!". Of course, who knows if something IS there or not...I had absolutely no idea, but it seems that indeed there was. These famous "two octaves in the bass register"!

So being "unchained" and having absolutely no idea on capacitors, oscillators, scales, music theory etc. what I found out FROM THE VERY FIRST MINUTES of playing with it, was that "the baby grew bigger" or "the boy went adult" or "the dog caught the bone". And it is not just a matter of the extremely improved linearity (that helps at the same time the better developing of my muscle memory), the almost equal intervals over the 7+ octaves and the demon bass frequencies that you can get in the lower register...

For me it is THE JOY. It seems that Thierry found the formula to set free Terpsichore that was well-hidden by Bob Moog in the insides of the circuit and I have the impression that he can set free the rest of the muses as well (maybe apart from one or two:)

Of course one can say: "Yes but is this the goal?" Well, for me it's the ONLY goal. This instrument being as challenging as it is to play, often makes people argue about "hitting this or that note" correctly, or "playing like a robot" or "not having enough soul" and indeed, that's very often the case. But let's not forget that the idea of feeling good and getting pleasure from playing music is fundamental and the nature of the theremin makes it the perfect instrument for that. The ESPE01 gives you the ground to develop that love for the theremin and unleashes the (full?) potential of a relatively cheap instrument that used to sound like Charles Bukowski reading "Love is a dog from hell" in a public theatre in the 70's (I love C.B.).

So if there are any more soul rebels / joy-seekers out there, please do yourself a favor -no matter how professional you are and what you play-, install the module, get yourself a subwoofer and play some music. I can guarantee that after having the module inside, you'll never play alone.

and to the Moog guys: Please buy some thousands of them and have them installed by default, it will save people lots of shipping fees.

"So, say an electronically inept thereminist from the northeast coast of the US was interested in having the mod done to his Etherwave Plus? Has there been any expansion in US installation options?" - Koschmar

My own bass mod, the YAEWSBM found here, is more of a DIY thing. Your best bet is either ship it to Thierry for him to install his ESPE01 module, or buy Thierry's ESPE01 module and get an EE friend to install it. Installing these decoupling boards isn't too involved, and probably doesn't require much in the way of retuning. Moog really should include it in the next spin of the board, as you can always trivially get coupling back if you want it (my design has a jumper for this).

The ESPE01 module does not simply decoupling, it lowers the coupling to a defined amount. It alters the timbres of the instrument slightly, too, by doing a kind of pre-mixer wave shaping which makes the sound more natural and organic. To get the best out of an Etherwave, I do not only recommend the installation of the ESPE01 module, but also a meticulous retuning of the internal oscillators to get a maximum of linearity which is not easy with that simple Etherwave circuit and requires a lot of experience. Since it is not everybody's thing to visit me in my atelier in France, or to ship their instrument here, I'm present at all major theremin events, i.e. "Hands off" or the different theremin academies which I organize almost everywhere in Europe, where I always offer an installation and fine tuning service, which has already often been appreciated by participants from the US and from South America.

"This mod sounds very intriguing. But I notice that before this week, this thread was dead for a couple years. So, say an electronically inept thereminist from the northeast coast of the US was interested in having the mod done to his Etherwave Plus? Has there been any expansion in US installation options?"

If you had Thierry's ESPE01 board and can get the board and instrument to Ithaca, NY I could install it for you. What you wouldn't get is Thierry's retuning for greater linearity, as that is way beyond my knowledge. Maybe Thierry can explain that process sometime.

The ESPE01 cost me an extra $200 when it revealed all the glaring deficiencies in my inexpensive keyboard amp - it it really buzzed when playing those low bass notes. Per Thierry's recommendation, I got a Behringer Ultratone K450FX and now all is well. The bass notes are nice but it would almost be worth the price just for the improvement in timbre!

"If you had Thierry's ESPE01 board and can get the board and instrument to Ithaca, NY I could install it for you." - senior_falcon

I successfully installed my first ESPE01 in an EWS yesterday. As far as I could tell the results were identical to that of my YAEWSBM circuit, though I didn't take any technical measurements. The bass range was extended as one would expect with decoupling, and the tuning didn't seem to be disturbed much. I think it would be best if the ESPE02 or whatever follows could incorporate the YAEWSBM recoupling jumper, so users could easily return it to near stock condition if they found they didn't like the decoupling for whatever reason (decoupling removes most bass timbre change).

Anyway, if anyone in the NY/NJ area has an ESPE01 and wants it installed in their working Etherwave, send me a PM. If you can bring it to me I'll do it for free (and check the tuning). The surgery only takes an hour or so.

The YAEWSBM played a significant role in my pursuit of developing the vocal sound I was after. Buffering was something I did not know how to approach until dewster posted one of his finest analog circuits.

For my purpose I use a modified version of the dew circuit. The YAEWSBM needs some improvement and I would not use this approach by itself for the EWS. The .6v voltage drop across the NPN transistor or mixing diode makes the amplitude too low on the input of the VCA. (Low Volume) It needs another transistor to bring the audio level up slightly and it could be adjustable. Also it needs to have a method of adding controlled distortion for a better sound.

I developed another board to go with the dewster board which gives my EWSthis sound. No one was interested so every thing was put away and I retired due to health issues. My brain has lost the spark!

Christopher

Edit: Here is my schematic and the issue may be in something I changed, R2 & R5 to 10k for the waveshape. On my board the R11 100k (again for waveshape) used with an I/O pin jumper to bypass my harmonic-exciter board is causing EWS signal attenuation so the true YAEWSBM may not be quiet and lives on.

"For my purpose I use a modified version of the dew circuit. The YAEWSBM needs some improvement and I would not use this approach by itself for the EWS. The .6v voltage drop across the NPN transistor or mixing diode makes the amplitude too low on the input of the VCA." - oldtemecula

Since the YAEWSBM I/O is AC coupled, I can't imagine that the forward voltage drop would have much (if any) influence over the gain.